The Host Club participates in the annual school festival. Tamaki's father and grandmother turn up there. However, the arrival of Eclair Tonnerre, a woman who Tamaki was told to take care of by his grandmother, brings an unforeseen turn of events. Haruhi also learns of Tamaki's history, and his entrance into the Suoh family.
After Ritsu walks in on Haruhi changing, he later joins the Host Club, but as a customer. When he insists on Haruhi as his host, the other hosts get nervous and the clients get excited. Tamaki starts to realize his feelings for Haruhi, and Ritsu nearly goes insane, while Haruhi remains blissfully oblivious.
When the son of a gangster, Ritsu Kasanoda, seeks Mori for tips on how to change his scary image and gain friends, the Host Club immediately jumps at the opportunity to change his image, making many humorous results of their efforts. The members of the Host Club also frequently call him Casanova and bossa nova. However, Ritsu ends up discovering Haruhi's secret.
Haruhi's class has a Halloween event - The Halloween Special Fear Trial Tournament- in which groups do their best to scare the living daylights out of each other! The class rep isn't so keen on this idea, though, and enlists Haruhi to help him. Kaoru, meanwhile, contemplates a sad truth. Nekozawa decides to scare the group of Haruhi, Kaoru, Hikaru, and the class rep.
A prequel that tells the story of how the twins were convinced to help form the club, including the "Which One is Hikaru?" game that they always played, including their past with the maid who led them to believe that no one would ever be able to tell them apart, and the cruel trick that they played on a girl in middle school.
The girls from St. Lobelia's Zuka Club finally manage to rope Haruhi into their academy, and it is up to the Host Club boys and Ranka to save her from Benio Amakusa stealing her first kiss - until Kyouya reminds them of Haruhi's real first kiss in a previous episode. The episode ends with the Lobelia's Zuka Club chasing Haruhi around the stage, attempting to steal her second kiss.
Honey has a younger brother Yasuchika, but he has a huge grudge against his sibling. It turns out the reason for his brother's grudge is that Honey eats too many cakes, causing Yasuchika to freak out.
During summer vacation, Haruhi gets a part-time job in a pension at Karuizawa. She feels guilty at first for not saying anything to the rest of the Host Club, until they drop in unannounced. A contest erupts when they realize there is only one remaining room at the pension. Hikaru and Kaoru win by using their brotherly love act. When Haruhi's middle school friend visits, things take a turn for the worst.
Honey gets his first cavity, and the number one rule until the cavity is fixed is no sweets. He then takes his frustration out on Mori, who is being strict on Honey, but Honey realizes that Mori was punishing himself for not telling Honey to brush his teeth twice.
Tamaki enlists the help of Renge in teaching Nekozawa to become the princely figure his little sister is convinced he is and help him face his fear of light, eventually leading to him saving his sister from a large, unfriendly cat, leading her to be convinced of his bravery despite the wig and cloak that he wears.
Interested in the unknown ways of a "commoner's lifestyle", the Host Club makes an unannounced appearance at Haruhi's house to meet her family and see how she lives. Tamaki realizes how independent Haruhi is and some of the reasons why.
St. Lobelia Girl's Academy's Benio Amakusa, head of the Zuka Club, chances upon Haruhi and, instantly recognizing that she is a girl, tries to convince her to join her school and her club. Convinced that Haruhi will leave them, the boys dress up as girls to show Haruhi that she "can have big brothers AND big sisters - all in one!" Haruhi reveals that she came to Ouran for a reason, and says that she was never planning to leave for Lobelia in the first place.
Renge, an intense young woman obsessed with dating sims, declares herself the Host Club’s new manager! Her first order of business: give each of the Hosts a "dark side."
The Host Club finds out that one of their regular customers, one of the few that skips from host to host regularly, is having trouble with her fiancé. The group then cooks up a plan to help, involving a dance, a kiss, and a big spotlight. Unfortunately, in the process, Haruhi has her first kiss; but not with the fiancé, but with the fiancée.
Ouran High is a school for the extremely wealthy or, in Haruhi's case, the extremely talented. But no amount of talent will help when Haruhi accidentally drops an eight million yen vase in a music room. The vase was the property of Ouran High School Host Club, a group of attractive young men who, for a fee, provide their time and affections for their lovesick clientele: the female students. Fascinated by this strange new specimen, a poor and clumsy commoner, they force Haruhi to work for them until the debt is repaid; but they get a lot more than they bargained for...